Airborne mineral aerosols emitted in high-latitude regions can impact radiative forcing, biogeochemical cycling of metals, and local air quality. The impact of dust emissions in these regions may change rapidly, as warming temperatures can increase mineral dust production and source regions. As there exists little research on mineral dust emissions in high-latitude regions, we have performed the first study of the physico-chemical properties of mineral dust emitted from a sub-Arctic proglacial dust source, using a method tailored to the remote conditions of the Canadian North. Soil and aerosol samples (PM 10 and deposited mineral dust) were collected in May 2018 near the € A'€ ay Ch u (Slims River), a site exhibiting strong dust emissions. WHO air quality thresholds were exceeded at several receptor sites near the dust source, indicating a negative impact on local air quality. Notably, temporally averaged particle size distributions of PM 10 were very fine as compared to those measured at more well-characterized, low-latitude dust sources. In addition, mineralogy and elemental composition of ambient PM 10 were characterized; PM 10 elemental composition was enriched in trace elements as compared to dust deposition, bulk soil samples, and the fine soil fractions (d < 53 mm). Finally, through a comparison of the elemental composition of PM 10 , dust deposition, and both fine and bulk soil fractions, as well as of meteorological factors measured during our campaign, we propose that the primary mechanisms for dust emissions from the € A'€ ay Ch u Valley are the rupture of clay coatings on particles and/or the release of resident fine particulate matter.

Mineral dust is a natural tracer of atmospheric composition and climate variability. Yet, there is still much to be known about the Southern Hemisphere dust cycle. Major efforts have attempted to solve the puzzle of the origin of the potential source areas contributing dust to the Southern Ocean and East Antarctica. Here we present a comprehensive geochemical characterization of a source area, whose role as a dust supplier to high latitude environments has significantly been underestimated. Sediments collected within the major dust-producing areas along the Namibian coast in Southern Africa (Kuiseb, Omaruru and Huab river catchments and the Namib Sand Sea region), were analyzed for radiogenic isotope ratios and rare earth element concentrations. We find that during warm periods, the Southern African dust signature can be found in archives of the Southern Hemisphere, especially in the Atlantic sector of the Southern Ocean and peripheral areas of the East Antarctic plateau.

Mineral dust is a natural tracer of atmospheric composition and climate variability. Yet, there is still much to be known about the Southern Hemisphere dust cycle during the last Pleistocene. Major efforts have attempted to solve the ‘puzzle’ of the origin of the potential source areas that contribute dust to the Southern Ocean and East Antarctica (EA). Here we present a comprehensive geochemical characterization of an important potential source area, which role as a dust supplier to different environments of the SH has significantly been underestimated, that is, the Southern Africa (SAF) region. On the basis of Sr-Nd-Pb isotope ratios and rare earth element concentrations analyzed in sediments collected along the major dust-producing areas in the Namibian coast (Kuiseb, Omaruru and Huab riverbeds and the Namibian sand sea region), this study demonstrates for the first time that SAF emerges as the second most important dust source to EA during interglacial times.

&lt;p&gt;Identifying the provenance of mineral dust depositions in Antarctica is crucial to reconstruct Southern Hemisphere (SH) atmospheric circulation, validate numerical models, evaluate their contribution as micronutrients in the Southern Ocean and assess their control on the climate changes. For the last few decades, it has been demonstrated Southern South America (SSA) is the main precursor of dust reaching Antarctica during both ice ages and interglacial periods (e.g. Gili et al., 2017, 2016). However, the origin of modern dust depositions on the Antarctic continent is still poorly constrained. Back in the nineties, together with SSA, Australia, New Zealand, and Southern Africa were firstly identified as dust contributors to East Antarctica (EA) (e.g. Delmonte et al., 2004a). Since then, only SSA and Australian dust sources benefited from detailed studies. While some works identified the Makgadikgadi and Etosha Pans as southern Africa's major mineral dust sources in the SH, it was not until recently the Namib Desert coastal areas were described as another important regional dust sources. Within the Namib Desert and along the coast, the Kuiseb (K), Omaruru (O) and Huab (H) dry riverbeds are the three main areas identified as the dustiest ones with the higher frequency of dust emission events (Von Holdt et al., 2017). Here we use Sr, Nd and Pb isotopes (measured on HR-MC-ICP-MS) to characterize and evaluate the influence of this region in Southern Africa as a dust source to EA. Samples collected in K, O and H desertic areas were analyzed together with snow samples collected along a ~250 km N-S transect (defined from the coast to inland) at seven different sampling sites in the surroundings of Dronning Maud Land, EA. In addition, using the bulk of the Huab region, dust aerosols were generated into an atmospheric simulation chamber (CESAM) to reproduce, mechanically the saltation and sandblasting processes responsible for the release of mineral dust in natural conditions. Our isotopic results show Namibia&amp;#8217;s coast emerged as another possible source end-member, together with some regions in SSA, that supply dust to EA during warmer periods.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Delmonte, B., Basile-Doelsch, I., Petit, J.R., Maggi, V., Revel-Rolland, M., Michard, A., Jagoutz, E., Grousset, F., 2004. Comparing the EPICA and Vostok dust records during the last 220,000 years: stratigraphical correlation and provenance in glacial periods. Earth-Sci. Rev. 66, 63&amp;#8211;87.&lt;/p&gt;&lt;p&gt;Gili, S., Gaiero, D.M., Goldstein, S.L., Chemale, F. Jr., Koester, E., Jweda, J., Vallelonga, P., Kaplan, M.R., 2016. Provenance of dust to Antarctica: a lead isotopic perspective. Geophys. Res. Lett. 43. http://dx.doi.org/10.1002/2016GL068244.&lt;/p&gt;&lt;p&gt;Gili, S., D.M. Gaiero, S.L. Goldstein, F. Chemale, J. Jweda, M.R. Kaplan, R.A. Becchio, and E. Koester (2017). Glacial/interglacial changes of Southern Hemisphere wind circulation from the geochemistry of South American dust. Earth Planet. Sci. Lett., 469, 98-109, doi: 10.1016/j.epsl.2017.04.007.&lt;/p&gt;&lt;p&gt;Von Holdt, JR., Eckardt FD., and Wiggs GFS., 2017. Landsat identifies aeolian dust emission dynamics at the landform scale. Remote Sensing of Environment 198., 229&amp;#8211;243.&lt;/p&gt;

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